The invention relates to a motorcycle clutch for a drive connection between an engine and a transmission of a motorcycle.
Such a clutch is known from EP 0 780 591 B1. In this document, problems which may occur in motorcycles are described. In particular, in types of higher performance motorcycles, in the partial load range and during motor braking, the clutch, upon decreasing engine torque, increasingly becomes a rigid drive connection between the engine and the driven rear wheel, with the consequence that the rear wheel tends to swerve or jump.
Further, it is described that, for decreasing the shifting forces of a clutch for a motorcycle, EP 0 098 749 A1 teaches to configure a clutch spring to engage the clutch only for part of the largest transferable torque, and to apply the remaining clutch force hydraulically. In this known clutch, it is considered to be disadvantageous for the function of the drag torque (to which EP 0 780 591 B1 is directed) that the smallest transferable torque is determined by the clutch spring which must be sufficiently dimensioned for driving the crankshaft through the rear wheel. Further, it is explained that, in this known clutch, no sensitive control of the admission pressure of the clutch is possible, since the hydraulic pressure is substantially relieved upon actuating the shift valve.
In order to configure a clutch for a motorcycle, such that the torque transmission between the engine and the driven rear wheel in a predetermined range enables an advantageous compensation of possible drive side irregularities during motor braking, independent of the closing force of the clutch spring, EP 0 780 591 B1 teaches the provision of a controller with which it should be possible to admit the pressure body of the clutch with a force opposite to the closing force of the clutch spring in accordance with the engine load.
However, this embodiment of a motorcycle clutch is disadvantageous in view of the fact that large operating forces of the clutch lever of motorcycle clutches may still be present due to the limitations of the installation space, since, in particular, in motorcycles having a large cylinder capacity, very large clutch spring forces have to be applied for transmitting the engine torque. These forces have to be overcome manually when disengaging the clutch, which in turn results in large operating forces.